histone base

n.
  1. The alpha-amino acids arginine, histidine, and lysine that are basic because of their respective side chains of guanidine, imidazole, and an amine group.hexone base
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.